Quarter-squares: a(n) = floor(n/2)*ceiling(n/2). Equivalently, a(n) = floor(n^2/4).

Terms

a(0) =0a(1) =0a(2) =1a(3) =2a(4) =4a(5) =6a(6) =9a(7) =12a(8) =16a(9) =20a(10) =25a(11) =30a(12) =36a(13) =42a(14) =49a(15) =56a(16) =64a(17) =72a(18) =81a(19) =90a(20) =100a(21) =110a(22) =121a(23) =132a(24) =144a(25) =156a(26) =169a(27) =182a(28) =196a(29) =210